Barley (Hordeum vulgare L.) seeds contain at least five proteins with chitinase (CH) activity. Two of these (CH1 and CH2) are found primarily in the aleurone and endosperm tissues, and the other three (CH3, CH4, and CH5) are enriched in the embryo. From the bran fraction, three of these CHs (CH1, CH2, and CH3) were purified to apparent homogeneity. These three CHs have apparent molecular masses of 27, 34, and 35 kilodaltons and isoelectric points of 9.3, 9.2, and 8.7, respectively. CH2 and CH3 have amino terminal sequences resembling a portion of the chitin-binding domain of lectins and other plant defense proteins. CH 1 lacks this domain. All three CHs exhibit antifungal activity and inhibit the mycelial growth of some species of Trichoderma and Fusarium in vitro. During the early period of imbibition by seeds, two of the embryo-associated CHs are selectively released into the surrounding aqueous medium. CHs2 (EC 3.2.1.14) catalyze the hydrolysis of 1(1,4) linkages between N-acetylglucosamine (2-acetamido-2-deoxyglucopyranoside) residues in the linear homopolymer, chitin.

A barley aleurone cDNA library was screened using (32)P-labeled cDNA prepared by reverse transcription of mRNA from aleurone layers treated in the presence or absence of gibberellic acid (GA). Besides α-amylase cDNA clones, another set of clones representing an abundant mRNA in aleurone cells was identified. Messenger RNA hybrid-selected by a prototype clone of this group (clone 10) was translated in vitro to yield a 36 kDa protein. Analysis of the DNA sequence and the predicted amino acid sequence of the protein product of this clone indicates that this gene codes for a protein with homology to endochitinases from tobacco and bean. In addition, the predicted amino acid sequence includes a stretch that is closely related to a cyanogen bromide cleavage fragment from an endochitinase isolated from barley endosperm. The structural genes for endochitinase are present as multiple copies on barley chromosome 1. mRNA detectable by this clone increases in abundance in barley aleurone cells incubated in the absence and in the presence of GA. Western blot analysis of proteins from aleurone and endosperm tissues indicates the presence of multiple endochitinases differing in molecular size. Possible mechanisms for the occurrence of multiple forms of endochitinases and their biological significance are discussed.

Crude protein extracts were made from kernels of 12 cultivars each of maize, sorghum and wheat. These preparations were fractionated on sodium dodecyl sulfate (SDS)‐polyacrylamide gels and subjected to Western blot analyses. Bands corresponding to chitinases and β‐glucanases were identified immunologically (Western blots) and on activity gels. Ribosome Inactivating Protein(s) (RIP) and permatins were identified immunologically. In maize, two chitinase bands (25–29 kDa) were seen in all cultivars, and a third band of about 23 kDa was detected in 7 of the 12 cultivars. Two or three β‐glucanase bands of sizes between 24 and 36 kDa (probably a mixture of 1,3–β‐ and 1,3–1,4‐β‐glucanases) were detected in blots of SDS gels, and one band was detected in activity gels (1,3‐β‐glucanase). In sorghum, one chitnase band of approximately 29 kDa, and two or three additional bands ranging in size from 21–24 kDa were observed. Only one β‐glucanase band was identified, with an estimated molecular weight of 30 kDa. All bands that appeared on Western blots of SDS gels corresponded to bands detected on activity gels. In wheat, one chitmase band of around 20 kDa, one β‐glucanase band of about 30 kDa and one RIP band of about 30 kDa were identified. Permatins (molecular weight about 22 kDa) were identified in maize, sorghum and wheat, with the different cultivars having varying amounts of permatins.

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A 37-kDa protein purified from rice thylakoid membranes has been identified as a ferredoxin-NADP+ oxidoreductase based on its catalysis of the reduction of nitro blue tetrazolium via NADPH and its recognition by antibodies against ferredoxin-NADP+ oxidoreductase. Amino acid sequences determined from tryptic fragments of the enzyme further confirm the identity of the protein and show the presence of unique sequences at the amino-terminus.